Condenser section



Feb. 18, 1941. M GEQRGIEV 2,232,320

CONDENSER SECTION Filed Feb. 25, 1938 INVENTOR ATTORN Patented Feb. 18, 1941 PATENT OFFICE I 2,232,320 CONDENSER SECTION Alexander M. Georgiev, Dayton, Ohio, usignor to General Motors Corporation, Detroit, Mich, a

corporation of Delaware Application February 23, 1938, Serial No. 191,886

8 Claims. (Cl. 175-415) This invention relates generally to the manufacture of electrical condensers, and particularly electrolytic condensers, having to do with the formation of condenser sections or bodies with integral terminal attaching portions, and a method for constructing the same.

-It is one oi the oblocts of this invention to provide a condenser body or section with integrally formed terminal attachment portions, without in-' volvlng an undue waste of electrode material.

Another object of this invention is to provide a compact condenser section with terminal attaching portions without material reduction of capacity of the completed unit for the quantity of the electrode material used. I

Another object of the invention is to provide an integrally formed terminal attaching portion for a convoluted electrode strip. by the use of a minimum of electrode material.

Another object of this invention is to provide a terminal union for a condenser section without introducing the possibility of galvanic action and/or anodic corrosion.

Another object of the invention is to provide a method for manufacturing condenser sections with the least amount of labor and time consumed, and with a substantial saving of material, thereby reducing the ultimate cost of the condenser section.

Another object of the invention is to provide a method of manufacturing condenser sections' whereby terminal attachinl portions of suitable characteristics may be formed coincident with the winding of the electrodes and spacers, and without adding to the cost of manufacture.

Further objects and advantages of the present invention will be apparent from the following descniption, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

Fig, 1 is a schematic showing illustrating one step in the formation of a condenser section according to the present invention.

Figs, 2 and 3 illustrate other and succeeding steps in the formation of the condenser section shown in Fig. 4.

Fig. 4 illustrates one form of a completed condenser section, with alternative means for attaching a terminal member.

, In the manufacture of electrical condensers, the major problem in the use of very thin electrode material in conjunction with spacers in convolut'ed form, consists in establishing a. dependable and inexpensive connector between the electrodes and the condenser terminals. The conventional folding of the ends of'the foil or electrode material in the shape of a tab has the drawback of using up a very long strip of the electrode material for the purpose of preparing the tabs.

' circuits.

Since the thin foil requires many layers, sometimes 20 or 30, in order to insure a mechanically strong terminal connector, there is thus used. a considerable portion of material for tab formation that does not enter into the condensing function of the unit. Such a great number of layers requires theme of a substantial portion of the total length of the electrode material in making the terminal connections, and this means a considerable waste of material, that is, of both electrode material and spacer material. Furthermore the folding of the electrode material into 20 or 30 layers requires extra labor and time which adds to the cost of manufacture of the condenser section.

Another problem in the use of strip material in convoluted form, particularly with condensers used in radio, is the impedance to high frequency The successive turns of the electrodes act to uce currents-in the opposite direction, which becomes of great moment in radio circuits, or where circuits of high frequency obtain.

Inovercoming these difllculties and objections, I accomplish the statedsnd other oblects by forming the terminal attaching portions of the electrode material coincident with the first few turns in the process of winding the electrodes and spacers. In accomplishing this, I draw the strips of the electrode material and spacers from the supply rolls, and dispose their ends on the winding mandrel such that the two spacers are centered in the desired manner for the completed winding, and with'the strips of electrode material each laterally displaced or oi'fset so as to have an edge portion extending beyond the edge ofthe centered-spacers. With the strips so adjusted, 1 wind the materials into a cylindrical or tubular body having the desiredsmount of material for the capacity contemplated. While the strips are being wound, and during the flrstfew convolutions thereof, 1 cause the electrode strips to gradally roadlust themselves to a substantially centered relation with respect to the spacers, and thereafter continue the winding with all of the strips respectively centered or in aligned relation. By winding the strips in this form, I produce all; each end of the tubular body a conical'spiral of exposed electrode material, which forms a. convenient attaching portion for a lead or terminal member, as the case may be, having a most em cient electrical connection with the body'or active portion of the respective electrodes. To these exposed electrode portions, I attach my leads or terminals by either welding or by riveting. n the other hand, I may make use of the electrode extensions as connectors by securing them directly to a terminal member carried by an in sulaior closing the casing, where they may be adopted as an exterior terminal.

with particular reference to the drawing, it lllustrates a mandrel, upon which the condenser sections are to be wound, and which is driven by means of a shaft I2. A loose assembly or pile of condenser material to be wound is drawn from the supply rolls and is adjusted upon the mandrel ID, the pile of materials comprising a first spacer l3, a first electrode strip or foil l4, a second spacer l6, and a second electrode strip or foil I. These strips are generally centered and piled in alternate order in that there is a spacer against which is an electrode strip, which in turn is covered by a second spacer, and on top of which is a second electrode strip. The spacers are of greater width than the electrode strips, so that in case of accidental displacement of the electrode strips there will be little or no likelihood of a short circuit between them.

As illustrated in Fig. 1, after drawing these condenser strips or foils over the mandrel, I leave the spacers l3 and I6 centered therewith, but I displace the foil l4 to the left so that it extends beyond the edge of the spacer l2 as indicated at 20. The electrode strip I8, I likewise displace tothe right as indicated at 22. It will be noted that though the ends of the electrodes 14 and I8 are offset, they are slightly out of parallel, and in fact having an appreciable taper toward the supply rolls. This is because the supply rolls are centered for the purpose of providing an assembly of strips that are substantially centered.

With'the condenser strips so adjusted, I rotate the mandrel through a certain number of revolutions to wind the condenser section to the desired capacity. During this rotation of the mandrel the pile of condenser strips will be wound upon the mandrel in tubular form having a central opening equal to the cross-section of the mandrel, and the displaced or offset electrode strips will rapidly but gradually assume a centered relation with respect to the spacers, which coincidentally forms a suitable terminal attaching portion at each end of the condenser section while the section is being wound to capacity, and with no further attention given to it than the initial offsetting or displacing of the ends of the electrode strips at the time that the strips are being attached to the mandrel preparatory to winding.

The condenser section thus far formed, provides a hollow cylindrical or tubular section, characterized by exposed electrode portions at each end thereof. In further manipulating this winding toward the ultimate end, I may collapse or substantially flatten the tubular section into a form comparable with the illustration of Fig. 2, in which there is at least one thin portion 28, and in which the central passage of the condenser section has been practically done away with, or the opposite surfaces of the passage brought into substantial engagement as indicated at 32. This forms what may be called a wafer or a packet of condenser material, and is generally indicated at 34. As indicated in Fig. 2, the complete flattening or collapsing of the tubular portion provides the two thinned portions ill and 36 connected by the plane portions 38 and 40. While I have illustrated the completely collapsed form, as shown in Fig. 2, I contemplate any other 001- lapsing of the tubular portion such as oneof tear-drop or non-symmetrical cross-section, or one in which but a single thinned edge 38 is formed, and which involves substantially a fold of the strips transverse to their length, or across their convolutions.

A further step in completing the formation of the condenser section may involve rolling the packet or wafer upon itself, such as by starting with the thinned edge 30 and bending up and rolling it over tightly, or in substance folding the edge 30 against the plane portion 40, after which the remainder of the packet is wrapped around the edge portion 30 to complete the bundle of condenser material substantially as illustrated in Fig. 3, and indicated at 42. This step results in a generally rounded bundle of inter-leaved and alternating strips of spacer and electrode material arranged generally in a contour simulating the capital letter G, or otherwise in which the several strips have a curved extent from beginning to end, comprising the reverse turns as indicated at 44, 46 and 48.

The resulting body from these steps is illustrated in Fig. 4 in which the bundle 42 provides the exposed electrode extensions 20 and 22, comprising conical spirals of the exposed electrode material adapted for terminal attachment. In attaching connectors or terminal leads to the terminal attaching portions 20 and 22, I do so in a manner to eliminate galvanic action and/or anodic corrosion which is likely to occur in the instance of the electrolytic condensers, if use is made of dis-similar metal or of non-filming metals. After the bundle 42 is formed, I pinch together the overlapping convolutions of the exposed electrode extensions, and then either weld the conductor 44 to the flattened and compacted electrode edges, as indicated at 46, or else I at tach the lead 44 by means of a hollow rivet 48, passing through the exposed electrode edges as indicated at the right in Fig. 4. I prefer to use leads and rivets of the same film forming metallic content as that of the electrode material, thereby preventing the occurrence of any galvanic action and/or anodic corrosion between or at the juncture of either the electrode material, the leads or the attaching means. If the leads were to be soldered or otherwise afllxed by any similar means, that involves the use of dissimilar metals galvanic action or anodic corrosion is likely to be manifest.

Thus, in manufacturing condenser sections, I provide a method of procedure in which I arrange electrode or foil strips on a mandrel with the spacers and the foils or electrodes initially displaced or oifset, and spirulate or wind the strips in convoluted form, during which the electrode strips become properly centered or substantially directly superimposed in relation to the spacers.

After this I flatten the tubular or cylindrical form thereby presenting a flattened body, which flattened form I cause to be again spirulated or wound, to provide a compact bundle in which the strip or layers are each reverse curved, and any internal spacing substantially done away with. To the exposed margins of the electrode material of this compact bundle, I aflix appropriate connecting means by either welding or riveting.

It will be noted that each of the electrode strips at the start of the winding, forms a conic spiral telescoped portion extending beyond the edge of the spacers, in which portion the successive convolutions of the electrode material are in contacting engagement, so that when pressed together incident to welding or riveting the connector or lead thereto the successive convolutions are brought into electrical conductivity at ment is made, the greater number 'of electrode convolutions that are bonded, and consequently the greater the reduction in impedance. In practice I may telescope either both of the electrode'strips, or I may telescope but one of the strips. and I may pinch the exposed electrode edges and attach the connecting lead at any point in the process 0! formation of the section. That is to say, I may connect the electrode edses with the lead, just after the body is removed irom the mandrel, or I may connect the lead the electrode edges just after the hollow cylinder has been flattened to the form shown in Pig. 2. Obviously I may adopt the condenser body with the attached leads, in either instance without pursuing the subsequentsteps described hereinabove. In other words, instances to use the hollow cylinder with attached leads and without flattening, as the form to be assembled, or I may elect in other ininstances to use the flattened form with attached leads and without thesecond rolling as the form to be assembled. Though contemplationishadotthose forms,it-is preierredto form the spirulated body into the compact form illustrated and claimed, since the available mounting space is usually limited, especially inradio installations.

The resulting article of manufacture is one in which the electrodes and spacers arein compact form and is encompassed within small physical dimensions. The foil margins or electrode members are telescoped in the course or winding suiiiciently to establish a connector integrai with the electrode itself. It is found in,

practice that some 6 to 10 convolutions at the starts! the winding are suflicient to provide the necessary material to provide a satisfactory con- The number of initial co'nvoiutions necessary to form a connection will depend upon its ultimate desired length, and will tan-into account whether leads or connectors are to be I may elect in some 2. Theprocess of making electrolytic condensers having electrodes of uniform width and spacers of greater width inconvolute relation, comprising the steps in combination, laterally displacing the ends of electrode strips for the b iirst convolution so that each electrode strip projects at one edge beyond a spacer edge, and decreasing the displacement for each successive convolution until the strips of electrode material and spacers are directly superimposed in centered relation, and continuing with successive convolutions until the desired capacity is attained. p

3. The process of making electrolytic condensers having electrodes and spacers in convolute'relation, comprising the steps in combination, selecting electrode strips of continuously uniform width and spacers 01 greater width and arranging them in alternating superposed relation with their ends on a winding mandrel, oflgo setting the ends of the electrodes beyond the, opposite edges of'the spacers'at the start of the convoiutions to provide terminal attaching portions, spirulating the oiiset electrodes with interposed spacers into a substantially hollow cylinder, and rapidly decreasing ,the offset of the electrodes for the tint rew convolutions until the are substantially centered and have their edges in alignmnt and thence spirulating the superimposed electrodes and spacers to a.

eflect the desird capacity. 7

4. The process of making electrolytic con- .densers having electrodes and spacers in convolute relation. comprising the steps in combination, shifting the starting ends of the electrodes laterally beyond the edges of the spacers, spira-- lating the electrodes and spacers and coincidentally drawing in the electrodes toward a common centered position to rapidly eliminate the initial shift (or the bulk of the convolutions, thence spiruiating the electrodes and spacers in centered'relation to form a hollow, cylinder 'of desired capacity, flattening the cylinder to formathinedgeacrossthebodytransverseto the'convolutions, spirulating the'flattened body byroliingthethin-edgeinnermost,andthence securing terminal leads to the-shifted portions otthe electrodes.

6. Themethodol'formihg eondensersections, thestcpsmeombinamadiusting apairotspacersincenteredrelationonawinw 

